CHENNAI: With petrol prices on the slide and local administrations cracking down on diesel, the petrol-diesel ratio in new cars is clearly gasoline-led.

But the trend is just the opposite in used cars, where diesel's share of sales has grown nearly three times in four years and petrol's share has come down.

Auto experts say this shows there is latent 'aspirational' demand for diesel vehicles particularly from bigger cities where buying a new diesel car is increasingly becoming more difficult and expensive.

Nagendra Palle, CEO, Mahindra First Choice Wheels, said "Between 2011 to 2014, diesel's share of used car sales went up from 13% to 32% so it's obvious that part of the diesel car demand has now moved to used vehicles. The used car market grew at a 20% clip in 2015 and 2016 should see similar growth."

Compare this to the trend in new car sales. Currently the petrol-diesel mix in new cars is similar to that of used cars --around 34% diesel to 66% petrol. But this is down from 70% diesel and 30% petrol in 2012.

The slimming gap in fuel prices and the emissions-related mandates about diesel has shifted a substantial amount of diesel demand in new cars back to gasoline, say experts.

Part of the reason for the diesel demand in used vehicles comes from the rise in customer interest in SUVs. "While SUVs comprise 17% of all new vehicle sales, in the used car market they command around 20% of the total sales," said Palle.

Auto experts say the diesel skew is also the result of a sharp rise in diesel vehicle sales in 2012 and 2013 when the price differential between petrol and diesel was at its peak.

Mohit Dubey, CEO of auto portal Carwale, said, "The price differential between petrol and diesel has come down from a peak of 34 per litre in 2012 to around 10 right now. Between 2010-2013, diesels dominated the car market and all those vehicles are now coming into the used car space. The lag between new car and used car market is about 4-5 years - that explains the diesel dominance in the used car market."

In fact, segment leaders like Maruti Suzuki, Tata Motors and Hero MotoCorp have reported de-growth of 34.3 per cent, 45 per cent and 20 per cent, respectively giving a clear indication of a prolonged slowdown in the sector.